On January 26, the engine overbur hole of the "Mazda RX500" showcar owned by the Numage Transportation Museum started at the Hiroshima Mazda Daishu store in Hiroshima City, and the composition of the mysterious engine body has been revealed.
The RX500 show model exhibited at the Tokyo Motor Show in 1970 is a concept car designed by Shigenori Fukuda, who later became the director and head of Mazda's design department, and it is 10A in the midship of a sleek sports car form. It is equipped with a type rotary engine. It is a car that attracted attention with an advanced design that looks like it was worked on by Carrozzeria in Europe. It seems that there was a description that a 12A rotary engine was installed in the pumplet of the motor show, but in fact, it was equipped with a 10A peripheral port specification for racing. What has been sleeping in Mazda's warehouse with other concept models for a long time was overhauled when it was donated to the Hiroshima Transportation Science Museum (now Numaji Transportation Museum) operated by Hiroshima City, and it has been reproduced to a runable state and has been reached the present. It is. After running a demonstration at an event called the Hiroshima Motor Festival held at the Marina Hop Parking Lot in the fall of 2011, in addition to being seen mainly at the museum, it was regularly burned into the engine and kept in condition. It was in a state. However, in recent years, it has become difficult to start the engine even during the regular maintenance, and we will carry out an engine overhaul at the suggestion of Hidehiko Ito, a chroma who is in charge of maintenance, and refresh the condition of the engine. It has become a thing.
The engine overhaul was led by Takayuki Kawajiri, who has been working on the regeneration and tuning of the rotary engine at Hiroshima Mazda, while the engine overhaul was led by the race mechanic of Hiroshima Mazda HMR, Shota Tadashi. Kunio Matsuura, a Mazda OB who assembled the original engine at that time, is also present for the disassembly work. In the compression test before disassembling, the rear side showed almost the standard value, while the compression value on the front side was zero for two rooms, and damage to the Apex seal was suspected. If you remove the distributor and the front cover with built-in oil pump and remove the stuck flywheel by force, you can carefully remove the tension bolt next time, and finally be able to separate it into the main part and remove it. Masu. Mr. Matsuura said, "At that time, I was preparing the engine every day to participate in the spa 24 hours race in 1970. Meanwhile, I was ordered to prepare an engine to be installed in the show car, but I think we replied that we would prepare it as soon as it was a racing engine, but we can't assemble a special specification." Masu. Therefore, it seems to be a peripheral port specification that is difficult to handle for road cars. As it was disassembled, it turned out that the front housing was made of aluminum (for the initial Cosmo Sports L10A) and the other side housings were made of steel. Mr. Kawajiri said, "I guess that there was probably some problems with the rotor housing and side housing when it was reproduced in 2011, and some of it was replaced and processed for mass-produced cars." Mr. Matsuura also said, "The water jacket shape of the two rotor housings is different, and the shape of the exhaust port is not the same. You can see traces of struggling to process mass production parts. Still, factory-specific parts are used everywhere, and you can see that the original one we assembled. There are some sports kits that are sold, but there are only factory specifications that are not set and have no processing marks."
As a result of the overhaul, I found that one of the apex seal and the corner seal of the front rotor was sticking, which was the cause of zero compression. According to Mr. Kawajiri, it is better to uniformize the front and rear rotor housing, and the bearing metal of the front rotor is being baked, so it needs to be repaired, but other than that, the rotor sliding surface of the side housing is also beautiful. So, some of the seals were also likely to be used as they were. The stick cause of the Apex seal also seems to be caused by the sticking of sludge and carbon, so it does not seem to be a big problem. " When I disassembled the downdraft cab made by the Japanese vaporizer that was installed, I assembled the missing parts as they were, but I procured the parts and already repaired them," said Kawajiri. It is a show car, and there was almost no opportunity to drive for a long time after the last overhaul, so it doesn't seem to be decisively destroying the inside. Noritsu Tamura, curator of the Hiroshima Transportation Science Museum, said, "I was relieved to see that the inside was not in a desperate state. I think it would be good if we could somehow find the parts that were considered unusable in the previous overhaul, repair them, return them to the original state, and play them." Mr. Matsuura also said, "I never thought that we would be able to stand in the disassembly of the 10A engine for the race we worked on more than 53 years ago. I was shown something good today," he said with a smile.
I would like to see you again when the 10A engine playback for this race is completed and the day comes when the RX50o can run again.